The present invention relates to plastic reclosable fasteners with sliders for opening and closing the reclosable fasteners on plastic bags and the like and particularly to the method of making protruding end stops on the reclosable fastener to prevent travel of the slider past the ends of the fastener.
Plastic reclosable fasteners or zippers with sliders are well known in the art. The plastic zippers have profiles and include a pair of male and female fastener elements in the form of reclosable interlocking rib and groove elements with a slider for opening and closing the rib and groove elements. In the manufacture of thermoplastic film bags, a pair of these male and female fastener elements extend along the mouth of the bag and these male and female elements are adapted to be secured in any suitable manner to the flexible walls of the thermoplastic film bags. These elements may be integral marginal portions of such walls or they may be extruded separately and thereafter attached to the walls along the mouth of the bag. Various arrangements have been utilized heretofore to maintain the slider on the zipper. In one of the more conventional arrangements the slider includes a separator finger that extends down between the integral locking rib and groove elements as the slider is moved from one edge of the bag to the other edge of the bag. When the bag is opened, the only thing to stop the slider was the side seam at the edge of the bag when the slider finger comes into contact with it. This prior art is described in U.S. Pat. No. 3,790,992. In that patent there is disclosed an improvement wherein the heat seals that join the rib and groove elements are wider at one end than the second edge of the bag and the wider seal being of a width at least equal to the length of the slider from its closing end to the finger so that the slider will remain fully on the bag at the end of its travel when opening the bag. The patent points out that these seal areas provide stops for the slider. Another arrangement for providing stops at the end of the zipper is disclosed in U.S. Pat. No. 3,259,951. In that patent the opposite ends of the interlocking or mating strips are permanently joined or sealed to each other at the ends with stop members sealed between the opposite ends of these members to stop the longitudinal movement of the slider therealong.
It would be desirable to provide a plastic bag having a zipper that is operated by a slider wherein the zipper is terminated with protruding end stops formed from the zipper to prevent the slider from moving off past the ends of the zipper. With this arrangement it is not necessary to add an additional stop element to the zipper nor to rely on the strength of the seam at the edge of the bag for preventing the slider from moving past the ends of the bag. It would also be desirable to do this by a method that does not slow down the manufacturing process.